Preparation method and application of hierarchical pore nanosheet-shaped SAPO-34 molecular sieve with tenon-and-mortise-like structure
By introducing KIT-6 into SAPO-34 molecular sieve to regulate the morphology and synthesize a multi-level porous nanosheet structure, the problem of SAPO-34 molecular sieve deactivation due to carbon deposition in the methanol to olefins process was solved, and the activity and stability of the catalyst were improved.
Patent Information
- Application Number
- CN202510730348.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-06-03
- Publication Date
- 2025-09-16
AI Technical Summary
The existing SAPO-34 molecular sieve is easily deactivated by carbon deposition due to side reactions in the methanol to olefins process, resulting in a short catalyst life and low mass transfer efficiency.
KIT-6 was used as a silicon source to regulate the morphology of SAPO-34 molecular sieve, and a multi-level porous nano-sheet SAPO-34 molecular sieve with a mortise and tenon structure was synthesized. Micropores and mesopores were introduced to improve the mass transfer efficiency.
Significantly improve the catalytic performance and stability of the catalyst, extend the catalyst life, reduce mass transfer resistance, and reduce coke formation.
Smart Images
Figure CN120646859A_ABST
Abstract
Description
Technical Field
[0001] The present invention belongs to the technical field of molecular sieve preparation, and in particular relates to a preparation method and application of a multi-level porous nano-sheet SAPO-34 molecular sieve with a mortise and tenon structure. Background Art
[0002] Silicate phosphate aluminum molecular sieve (SAPO-n) developed by Union Carbide Corporation (UCC) is the third generation of molecular sieve after ZSM-5 and natural zeolite. It is composed of three [SiO4 4- ],[PO4 + ],[AlO4 - ] Microporous crystals composed of tetrahedrons have special water absorption and proton acidity, and due to the electronegativity of the skeleton, they also have exchangeable cations.
[0003] Within the SAPO series, SAPO-34 zeolite has a structure similar to chabazite, consisting of perpendicular, three-dimensional octahedral intersecting channels (0.38 nm × 0.38 nm) and a larger CHA cage (1.27 nm × 0.94 nm). It has attracted widespread attention due to its excellent hydrothermal and thermal stability, high-temperature framework resistance, and moderate acid strength. Aluminophosphate silicate (SAPO) zeolites are numerous, with over 20 different structures reported in the International Zeolite Association database. These SAPO zeolites are widely used in catalysis. As a key member of the SAPO series, SAPO-34 zeolite possesses unique catalytic properties, demonstrating excellent catalytic performance in reactions such as methanol to olefins and CO2 hydrogenation to ethylene.
[0004] SAPO-34 zeolite has a unique octahedral pore structure and moderate acidity, which makes it highly resistant to the diffusion of isomeric or heavy hydrocarbons and less resistant to the diffusion of light hydrocarbons. This results in high selectivity for C2-C4 olefins in the methanol-to-olefins (MTO) process. During the MTO process, SAPO-34 zeolite is deactivated by carbon deposition due to side reactions. Effectively controlling carbon deposition caused by side reactions and extending the service life of SAPO-34 zeolite catalysts are hot topics in MTO catalyst research and development.
[0005] Mesoporous silica materials (SBA-15, KIT-6, MCM-41, etc.) have attracted much attention due to their unique properties such as large specific surface area, large pore volume, adjustable pore size, and easy surface functionalization. By introducing materials with three-dimensional ordered mesoporous structures (such as KIT-6) as templates or mesoporous building blocks, mesoporous networks can be effectively introduced into the SAPO-34 framework. This not only exposes more active sites, but more importantly, it can provide efficient diffusion channels, significantly enhance mass transfer efficiency, promote the diffusion and discharge of macromolecular intermediates and carbon deposit precursors, thereby effectively alleviating pore blockage and ultimately improving catalytic performance and stability.
[0006] Therefore, the present invention develops a multi-level porous nano-sheet SAPO-34 molecular sieve with a mortise and tenon structure. Summary of the Invention
[0007] To address the aforementioned technical problems, the present invention provides a method for preparing and applying a multi-level porous nano-sheet SAPO-34 molecular sieve with a mortise-and-tenon structure. The present invention synthesizes a multi-level porous nano-sheet SAPO-34 molecular sieve with a mortise-and-tenon structure by adding KIT-6 as a silicon source to control the morphology of the SAPO-34 molecular sieve. The multi-level porous nano-sheet SAPO-34 molecular sieve synthesized by this method has a microporous structure, abundant mesopores within and between crystals, and a large specific surface area and pore volume. This significantly reduces material diffusion paths and greatly increases mass transfer rates, thereby reducing coke formation, extending catalyst life, and improving catalytic performance.
[0008] In order to achieve the above objectives, the present invention adopts the following technical solutions.
[0009] A method for preparing a multi-level porous nano-sheet SAPO-34 molecular sieve with a mortise and tenon structure, comprising the following steps: Step 1, preparing KIT-6; Step 2: uniformly mix the aluminum source and deionized water, and sequentially add KIT-6, a phosphorus source, and a template to obtain a mixed solution; Step 3: crystallize the mixed solution, separate, wash, dry and calcine the obtained solid product to obtain a multi-level porous nano-sheet SAPO-34 molecular sieve with a mortise-and-tenon structure.
[0010] Furthermore, in step 2, the aluminum source is one or a combination of pseudo-boehmite, aluminum isopropoxide or aluminum isobutoxide.
[0011] Furthermore, in step 2, the template agent is one or a combination of di-n-propylamine, diisopropylamine, diethylamine, and triethylamine.
[0012] Furthermore, in step 2, the phosphorus source is one or a combination of orthophosphoric acid, diammonium hydrogen phosphate or ammonium dihydrogen phosphate.
[0013] Furthermore, in step 2, the mass ratio of the aluminum source, the phosphorus source, the template, KIT-6 and water is 1:0.5~5:1~10:1~10:10~100.
[0014] Furthermore, in step 2, stirring and mixing are performed in a water bath at 20-40°C.
[0015] Furthermore, in step 3, the crystallization temperature is 100 to 260° C., and the crystallization time is 4 to 96 hours.
[0016] Furthermore, in step 3, the calcination temperature is 500-650° C., and the calcination time is 2-16 hours.
[0017] Furthermore, the specific preparation method of step 1 is: Step 1.1, mixing a template agent polyethylene oxide-polypropylene oxide-polyethylene oxide triblock copolymer (P123) with deionized water and a certain mass fraction of an acid, and magnetically stirring for a period of time until the polyethylene oxide-polypropylene oxide-polyethylene oxide triblock copolymer (P123) is completely dissolved to obtain a mixed solution 1; Step 1.2, adding a certain amount of co-solvent to the mixed solution 1, and magnetically stirring for a certain period of time until the solution is uniformly mixed to obtain a mixed solution 2; Step 1.3, adding a certain amount of silicon source to the mixed solution 2, stirring at a certain temperature for several hours, and transferring the obtained mixture into a high-pressure reactor for crystallization to obtain a solid product; Step 1.4: Separate, wash, filter, and dry the obtained solid product to obtain KIT-6.
[0018] Furthermore, in step 1.1, the acid is one or a combination of hydrochloric acid, nitric acid or phosphoric acid.
[0019] Furthermore, in step 1.1, the mass fraction of the acid is 25% to 50%.
[0020] Furthermore, in step 1.2, the co-solvent is one or a combination of methanol, ethanol, n-propanol, isopropanol, n-butanol or isobutanol.
[0021] Furthermore, in step 1.3, the silicon source is one or a combination of ethyl orthosilicate, propyl orthosilicate, butyl orthosilicate or acidic silica sol.
[0022] Furthermore, the mass ratio of the silicon source, the polyethylene oxide-polypropylene oxide-polyethylene oxide triblock copolymer (P123), the acid, water and the co-solvent is 1:0.1-10:0.5-10:1-30:0.1-10.
[0023] Furthermore, in step 1.3, the crystallization temperature is 100 to 260° C., and the crystallization time is 4 to 96 hours.
[0024] Furthermore, in step 1.3, stirring and mixing are performed in a water bath at 20-40°C.
[0025] Compared with the prior art, the present invention has the following beneficial effects.
[0026] The present invention provides a multi-level porous nano-sheet SAPO-34 molecular sieve with a mortise and tenon structure. KIT-6 is used as a silicon source in the SAPO-34 molecular sieve synthesis system to regulate the morphology of the SAPO-34 molecular sieve, and a multi-level porous nano-sheet SAPO-34 molecular sieve is synthesized. The introduction of the multi-level porous nano-sheet structure into the SAPO-34 molecular sieve can not only greatly reduce the mass transfer resistance, but also provide more pores, thereby improving the catalytic performance. BRIEF DESCRIPTION OF THE DRAWINGS
[0027] Figure 1 This is the X-ray diffraction pattern of the SAPO-34 molecular sieve synthesized in Example 1.
[0028] Figure 2 This is a scanning electron microscope image of the SAPO-34 molecular sieve synthesized in Example 1.
[0029] Figure 3 The nitrogen adsorption / desorption isotherm and BJH pore size distribution curve of the SAPO-34 molecular sieve synthesized in Example 1.
[0030] Figure 4 Example 1 Synthesis of ammonia temperature-programmed desorption curve of SAPO-34 molecular sieve. DETAILED DESCRIPTION
[0031] In order to have a clearer understanding of the technical features, objectives and beneficial effects of the present invention, the technical solution of the present invention is described in detail below with reference to the accompanying drawings, but it should not be understood as limiting the scope of implementation of the present invention.
[0032] A method for preparing a multi-level porous nano-sheet SAPO-34 molecular sieve with a mortise and tenon structure, comprising the following steps: Step 1, preparing KIT-6; Step 2: uniformly mix the aluminum source and deionized water, and sequentially add KIT-6, a phosphorus source, and a template to obtain a mixed solution; Step 3: crystallize the mixed solution, separate, wash, dry and calcine the obtained solid product to obtain a multi-level porous nano-sheet SAPO-34 molecular sieve with a mortise-and-tenon structure.
[0033] Furthermore, in step 2, the aluminum source is one or a combination of pseudo-boehmite, aluminum isopropoxide or aluminum isobutoxide.
[0034] Furthermore, in step 2, the template agent is one or a combination of di-n-propylamine, diisopropylamine, diethylamine, and triethylamine.
[0035] Furthermore, in step 2, the phosphorus source is one or a combination of orthophosphoric acid, diammonium hydrogen phosphate or ammonium dihydrogen phosphate.
[0036] Furthermore, in step 2, the mass ratio of the aluminum source, the phosphorus source, the template, KIT-6 and water is 1:0.5~5:1~10:1~10:10~100.
[0037] Furthermore, in step 2, stirring and mixing are performed in a water bath at 20-40°C.
[0038] Furthermore, in step 3, the crystallization temperature is 100 to 260° C., and the crystallization time is 4 to 96 hours.
[0039] Furthermore, in step 3, the calcination temperature is 500-650° C., and the calcination time is 2-16 hours.
[0040] Furthermore, the specific preparation method of step 1 is: Step 1.1, P123 is mixed with deionized water and a certain mass fraction of acid, and magnetically stirred for a period of time until P123 is completely dissolved to obtain a mixed solution 1; Step 1.2, adding a certain amount of co-solvent to the mixed solution 1, and magnetically stirring for a certain period of time until the solution is uniformly mixed to obtain a mixed solution 2; Step 1.3, adding a certain amount of silicon source to the mixed solution 2, stirring at a certain temperature for several hours, and transferring the obtained mixture into a high-pressure reactor for crystallization to obtain a solid product; Step 1.4: Separate, wash, filter, and dry the obtained solid product to obtain KIT-6.
[0041] Furthermore, in step 1.1, the acid is one or a combination of hydrochloric acid, nitric acid or phosphoric acid.
[0042] Furthermore, in step 1.1, the mass fraction of the acid is 25% to 50%.
[0043] Furthermore, in step 1.2, the co-solvent is one or a combination of methanol, ethanol, n-propanol, isopropanol, n-butanol or isobutanol.
[0044] Furthermore, in step 1.3, the silicon source is one or a combination of ethyl orthosilicate, propyl orthosilicate, butyl orthosilicate or acidic silica sol.
[0045] Furthermore, the mass ratio of the silicon source, P123, acid, water and co-solvent is 1:0.1-10:0.5-10:1-30:0.1-10.
[0046] Furthermore, in step 1.3, the crystallization temperature is 100 to 260° C., and the crystallization time is 4 to 96 hours.
[0047] Furthermore, in step 1.3, stirring and mixing are performed in a water bath at 20-40°C.
[0048] Example 1S1-SAPO-34.
[0049] 4.0 g of P123 was mixed with 142.55 g of deionized water and 7.32 g of 37% hydrochloric acid, and magnetically stirred for 4 hours until the P123 was completely dissolved to obtain a homogeneous solution. Then, 3.94 g of n-butanol was added thereto and stirred for 1 hour to form a transparent mixed solution. Then, 8.45 g of tetraethyl orthosilicate was added thereto. The resulting mixture was stirred at 35° C. for 24 hours, and the resulting granular mixture was transferred to a 100 mL reactor and hydrothermally crystallized at 100° C. for 24 hours. The resulting solid was separated, washed, filtered, and dried to obtain KIT-6.
[0050] 2.20 g of pseudo-boehmite was stirred with 43.54 g of deionized water for 30 min. After mixing evenly, 3.88 g of KIT-6, 4.64 g of phosphoric acid (mass fraction 85%) and 5.09 g of triethylamine were added. After magnetic stirring in a 30° C. water bath for 2 h, a mixed solution (sol) was formed.
[0051] The mixed solution was charged into a polytetrafluoroethylene autoclave, crystallized in an oven at 200°C for 32 hours, filtered, and the solid product was washed with deionized water to a pH of 7. The solid product was then dried in an oven at 80°C for 12 hours and calcined at 650°C (heating rate 3°C / min) for 12 hours to obtain a multi-level porous nanosheet SAPO-34 molecular sieve with a mortise and tenon structure.
[0052] The X-ray diffraction pattern of the multi-level porous nanosheet SAPO-34 molecular sieve of this type of mortise and tenon structure is shown in Figure 1 ; SEM images are shown in Figure 2 .from Figure 2Each side of the molecular sieve exhibits a mortise-and-tenon structure. This structure creates SAPO-34 nanosheets that expose more catalytically active sites and provide shorter diffusion pathways, preventing secondary reactions and reducing catalyst coking. This significantly improves the catalyst's activity, selectivity, and stability in the methanol-to-olefins reaction.
[0053] Examples 2 to 8.
[0054] The specific steps and synthesis conditions are similar to those in Example 1, except that the crystallization times of SAPO-34 molecular sieves are 4 h, 8 h, 16 h, 24 h, 48 h, 60 h, and 72 h, respectively. The synthesized SAPO-34 molecular sieves are named S2-SAPO-34, S3-SAPO-34, S4-SAPO-34, S5-SAPO-34, S6-SAPO-34, S7-SAPO-34, and S8-SAPO-34, respectively.
[0055] Based on Example 1, only some steps and crystallization conditions were changed in the following comparative examples, but SAPO-34 products with different crystallinity were obtained. For convenience, they are briefly described below.
[0056] Comparative Example 1D1 - SAPO-34.
[0057] The 3.88 g KIT-6 silicon source added in Example 1 was replaced with 10.00 g acidic silica sol (mass fraction 30%), and the remaining components and synthesis conditions were the same as in Example 1 to obtain SAPO-34 molecular sieve D1-SAPO-34.
[0058] Comparative Example 2D2-SAPO-34.
[0059] The 3.88 g KIT-6 silicon source added in Example 1 was replaced with 1.94 g calcined KIT-6 (without template P123), and the remaining components and synthesis conditions were the same as in Example 1 to obtain SAPO-34 molecular sieve D2-SAPO-34.
[0060] Comparative Example 3D3-SAPO-34.
[0061] The 3.88 g KIT-6 silicon source added in Example 1 was replaced with 10.00 g acidic silica sol (mass fraction 30%), and 1.94 g P123 was added. The remaining components and synthesis conditions were the same as in Example 1 to obtain SAPO-34 molecular sieve D3-SAPO-34.
[0062] Comparative Example 4D4-SAPO-34.
[0063] The 3.88 g KIT-6 silicon source added in Example 1 was replaced with 1.94 g calcined KIT-6 (without the template P123), and 1.94 g P123 was added. The remaining components and synthesis conditions were the same as in Example 1 to obtain SAPO-34 molecular sieve D4-SAPO-34.
[0064] Activity evaluation: The multi-level pore SAPO-34 molecular sieve with a mortise-and-tenon structure prepared in the examples and comparative examples was centrifuged, washed, dried and calcined to obtain an H-type SAPO-34 molecular sieve, which was then pressed into 20-40 mesh pieces.
[0065] Methanol was used as a model compound to evaluate the MTO reaction performance of the multi-stage pore S1-SAPO-34 catalyst with a mortise-and-tenon structure prepared in Example 1. The evaluation conditions were: a volume space velocity of 1.0 h -1 , the reaction temperature was 420℃, and the evaluation results are shown in Table 1.
[0066] Table 1 Evaluation results of MTO reaction performance on different SAPO-34 molecular sieves.
[0067] In the methanol-to-olefins (MTO) reaction catalyzed by the SAPO-34 molecular sieve prepared in Example 1, the methanol conversion rate was close to 100%, and the diene yield was 87.02%. The catalyst activity decreased significantly after 480 minutes, indicating that the catalyst began to deactivate. The SAPO-34 molecular sieves prepared in Examples 2 to 8 and Comparative Examples 1 to 4 all showed varying degrees of decrease in the methanol conversion rate, diene yield, and catalyst life in the MTO process. This is because the hierarchical nanosheet-like SAPO-34 with its mortise-and-tenon structure prepared in Example 1 can expose more active sites.
[0068] The specific embodiments described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.
Claims
1. A method for preparing a multi-level porous nano-sheet SAPO-34 molecular sieve with a mortise and tenon structure, characterized in that: The following steps are involved: Step 1, preparing KIT-6; Step 2: uniformly mix the aluminum source and deionized water, and sequentially add KIT-6, a phosphorus source, and a template to obtain a mixed solution; Step 3: crystallize the mixed solution, separate, wash, dry and calcine the obtained solid product to obtain a multi-level porous nano-sheet SAPO-34 molecular sieve with a mortise-and-tenon structure.
2. The method for preparing the multi-level porous nano-sheet SAPO-34 molecular sieve with a mortise and tenon structure according to claim 1, characterized in that: In step 2, the aluminum source is one or more combinations of pseudo-boehmite, aluminum isopropoxide, or aluminum isobutoxide; the template is one or more combinations of di-n-propylamine, diisopropylamine, diethylamine, and triethylamine; and the phosphorus source is one or more combinations of orthophosphoric acid, diammonium hydrogen phosphate, or ammonium dihydrogen phosphate.
3. The method for preparing the multi-level porous nano-sheet SAPO-34 molecular sieve with a mortise and tenon structure according to claim 1, characterized in that: In step 2, the mass ratio of the aluminum source, the phosphorus source, the template, KIT-6 and water is 1:0.5~5:1~10:1~10:10~100.
4. The method for preparing the multi-level porous nano-sheet SAPO-34 molecular sieve with a mortise and tenon structure according to claim 1, characterized in that: In step 2, stirring and mixing are performed in a water bath at 20-40°C.
5. The method for preparing the multi-level porous nano-sheet SAPO-34 molecular sieve with a mortise and tenon structure according to claim 1, characterized in that: In step 3, the crystallization temperature is 100-260° C., and the crystallization time is 4-96 hours; the calcination temperature is 500-650° C., and the calcination time is 2-16 hours.
6. The method for preparing the multi-level porous nano-sheet SAPO-34 molecular sieve with a mortise and tenon structure according to claim 1, characterized in that: The specific preparation method of step 1 is: Step 1.1, mixing a template polyethylene oxide-polypropylene oxide-polyethylene oxide triblock copolymer with deionized water and a certain mass fraction of an acid, and magnetically stirring for a period of time until the polyethylene oxide-polypropylene oxide-polyethylene oxide triblock copolymer is completely dissolved to obtain a mixed solution 1; Step 1.2, adding a certain amount of co-solvent to the mixed solution 1, and magnetically stirring for a certain period of time until the solution is uniformly mixed to obtain a mixed solution 2; Step 1.3, adding a certain amount of silicon source to the mixed solution 2, stirring at a certain temperature for several hours, and transferring the obtained mixture into a high-pressure reactor for crystallization to obtain a solid product; Step 1.4: Separate, wash, filter, and dry the obtained solid product to obtain KIT-6.
7. The method for preparing the multi-level porous nano-sheet SAPO-34 molecular sieve with a mortise and tenon structure according to claim 6, characterized in that: The mass fraction of acid is 25%~50%.
8. The method for preparing the multi-level porous nano-sheet SAPO-34 molecular sieve with a mortise and tenon structure according to claim 6, characterized in that: The mass ratio of the silicon source, the polyethylene oxide-polypropylene oxide-polyethylene oxide triblock copolymer, the acid, water and the cosolvent is 1: 0.1~10: 0.5~10: 1~30: 0.1~10.
9. The method for preparing the multi-level porous nano-sheet SAPO-34 molecular sieve with a mortise and tenon structure according to claim 1, characterized in that: In the step 1.3, the crystallization temperature is 100-260° C., and the crystallization time is 4-96 hours; stirring and mixing are performed in a water bath at 20-40° C.
10. Use of the SAPO-34 molecular sieve prepared by the method for preparing the multi-level porous nano-sheet SAPO-34 molecular sieve with a mortise-and-tenon structure according to any one of claims 1 to 9, characterized in that: Application of the SAPO-34 molecular sieve in methanol to olefins reaction.